| Abbreviation | Definition |
|---|---|
| UPO | Compiled update data (dBASE) |
| URI | List of Uniform Resource Identifiers |
| URIS | List of Uniform Resource Identifiers |
| URL | Internet shortcut (Universal Resource Locator) |
| URT | Utah Run-Length Encoded image file Bitmap graphics |
| USE | Log file |
| USP | PageMaker Printer font with U. S. ASCII extended character set |
| USR | User database ( Procomm Plus - Turbo C++ tour) |
| UST | Utau Sequence Text |
| USTAR | POSIX Tar Compressed file archive |
| USX | Unreal Tournament 2003 Static Mesh file |
| UT2 | Unreal Tournament 2003 Map file |
| UTX | Unreal Tournament Text file |
| UU | UUdecode - UUencode Encoded file archive ( ASCII) |
| UUD | UUencode Decoded file archive ( ASCII) |
| UUE | UUencode Encoded file archive ( ASCII) |
| UUT | Genesis 2000 file |
| UV2 | Jane's Combat Simulations file |
| UW | Unsigned Word Music file |
| UWF | UltraTracker WaveSample Music file |